Miniature or low profile electrical connectors are used extensively in applications wherein it is desirable to maintain the heights of the connectors as short as possible. For instance, miniature or low profile surface mount connectors are mounted on printed circuit boards and the space within an appliance in which the connectors and circuit boards are used is of a premium. The low profile of the connectors cause a variety of problems.
For instance, a problem in low profile surface mount connectors is that the terminals of the connectors have relatively short mating lengths which makes them susceptible to incomplete or partial mating. There is relatively little amount of space or height available to provide for a suitable contact beam length and to yield adequate beam deflection. Furthermore, in board-to-board connector applications wherein no mechanical connections are provided except the frictional engagement between the mating terminals, the possibility that the miniature or low profile connectors can be accidentally unmated by mechanical shock is significant. These considerations have necessitated incorporating either increased frictional engagement between the terminals (thereby increasing the force required to disconnect the connectors) or providing interlocking portions between the mating terminals or the connector housings. Such interlocking portions not only provide positive retention between the mating connectors, but they also can provide tactile feedback or other sensory indication that the connectors are fully mated. Often, however, such interlocking portions between the mating terminals or the connector housings can contribute to complicated molds or dies, and the positive retention can result in excessive mating and unmating forces which, in turn, render the connector and/or the printed circuit board assembly susceptible to damage or breakage upon mating and unmating.
Still further, in surface mount connectors, repeated mating and unmating can compromise the integrity of the solder joints between the surface mount terminals and the circuit traces on the printed circuit board. For this reason, solderable retention members (or "fitting nails") have been used to relieve the stress at the solder joints and to provide additional mechanical joint strength between the connectors and the board so that torsional stresses incurred during mating and unmating are not transferred to the solder joints. The strain relief provided by such solderable retention members is particularly important in connector pairs where the mating and unmating forces are relatively high and/or where the number of circuits is relatively low. However, the provision of adequate retention members or fitting nails in miniature or low profile surface mount connectors can be complicated and costly.
The present invention is directed to providing an electrical connector assembly of the character described above that employs various features that combine to facilitate the miniaturization of the mating connectors and to provide an efficient and very effective low profile connector assembly.